U.S. patent number 6,060,125 [Application Number 09/228,360] was granted by the patent office on 2000-05-09 for method and apparatus for controlling opening and closing speed of dispensing gun valve mechanism.
This patent grant is currently assigned to Nordson Corporation. Invention is credited to Hidetsugu Fujii.
United States Patent |
6,060,125 |
Fujii |
May 9, 2000 |
**Please see images for:
( Certificate of Correction ) ** |
Method and apparatus for controlling opening and closing speed of
dispensing gun valve mechanism
Abstract
Dispensing apparatus including a dispensing gun having a gun
body and a valve mechanism disposed in the gun body. The valve
mechanism is operatively coupled to a piston mounted for
reciprocating movement and the valve mechanism is operable between
opened and closed positions for selectively dispensing liquid from
the dispensing gun. A hydraulic actuator is operatively coupled to
the piston for moving the piston by way of an output of hydraulic
pressure. A flow control device is operatively coupled to the
hydraulic actuator for regulating liquid flow from the hydraulic
actuator and thereby controlling at least one of the opening speed
and closing speed of the valve mechanism. A method of dispensing
liquid in accordance with the disclosure includes holding a supply
of pressurized liquid in a liquid passage of the dispensing gun,
moving the piston under the force of hydraulic pressure to move the
valve mechanism from the closed position to the opened position,
and dispensing pressurized liquid from the gun.
Inventors: |
Fujii; Hidetsugu (Tokyo,
JP) |
Assignee: |
Nordson Corporation (Westlake,
OH)
|
Family
ID: |
11913928 |
Appl.
No.: |
09/228,360 |
Filed: |
January 11, 1999 |
Foreign Application Priority Data
|
|
|
|
|
Jan 12, 1998 [JP] |
|
|
10-016350 |
|
Current U.S.
Class: |
427/8; 222/518;
239/585.5; 427/424; 427/427.2; 427/427.3 |
Current CPC
Class: |
B05C
5/0225 (20130101) |
Current International
Class: |
B05C
5/02 (20060101); B05D 001/02 () |
Field of
Search: |
;427/421
;239/585.1,585.5,533.1,533.15 ;222/504,518 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dudash; Diana
Assistant Examiner: Calcagni; Jennifer
Attorney, Agent or Firm: Wood, Herron & Evans,
L.L.P.
Claims
I claim:
1. Apparatus for dispensing a liquid, the apparatus comprising:
a dispensing gun having a body,
a valve mechanism disposed in said body and operable between opened
and closed positions for selectively dispensing liquid from said
gun,
a piston mounted for reciprocating movement and operatively coupled
with said valve mechanism,
a hydraulic actuator operatively coupled to said piston for moving
said piston in response to hydraulic pressure, and
a flow control device operatively coupled between said hydraulic
actuator and said piston for regulating hydraulic fluid flow
delivered from said hydraulic actuator and acting on said piston
and thereby controlling a speed of movement of said valve mechanism
between said open and closed positions.
2. The apparatus of claim 1 further comprising a spring return
mechanism operatively coupled to said piston for returning said
valve mechanism to the closed position.
3. The apparatus of claim 1, wherein said hydraulic actuator
further comprises a pneumatic to hydraulic pressure converter that
receives an input of air pressure and outputs a corresponding
liquid pressure.
4. The apparatus of claim 1, wherein said flow control device
further comprises a flow regulating valve.
5. The apparatus of claim 1, wherein the gun body further comprises
a pre-loaded chamber of liquid to be dispensed when said valve
mechanism is in the opened position.
6. The apparatus of claim, 1, wherein said hydraulic actuator
further comprises a pressurized hydraulic fluid supply having a
pressurized output controlled by a motor.
7. The apparatus of claim 6 further comprising:
a sensor for sensing a relative speed of motion between the
dispensing gun and a substrate to be coated, said sensor being
operatively coupled to said motor so that the output of said
pressurized hydraulic fluid supply is controlled in proportion to
said relative speed of motion.
8. The apparatus of claim 1, further comprising:
a sensor for sensing a relative speed of motion between the
dispensing gun and a substrate to be coated, said sensor being
operatively coupled to said hydraulic actuator so that the output
of said hydraulic pressure is controlled in proportion to said
relative speed of motion.
9. A method of dispensing liquid from a gun including a valve
mechanism said valve mechanism operatively coupled to a piston,
said valve mechanism being disposed in a liquid passage of said gun
and movable between opened and closed positions under the force of
hydraulic pressure from a hydraulic fluid, the method
comprising:
holding a supply of pressurized liquid in the liquid passage,
moving the piston under the force of the hydraulic pressure to
thereby move said valve mechanism from said closed position to said
opened position,
adjusting the force of said hydraulic pressure by varying a flow of
the pressurized hydraulic fluid against said piston and thereby
varying a speed of movement of said valve mechanism to at least one
of said opened and closed positions, and
dispensing said pressurized liquid.
10. The method of claim 9, wherein the dispensing gun further
includes a spring mechanism for urging said valve mechanism to said
closed position, and the method further comprises:
reducing the force of said hydraulic pressure, and
returning said valve mechanism to said closed position under a
force of said spring mechanism to stop dispensing said pressurized
liquid.
11. The method of claim 9, wherein the step of holding said
pressurized liquid further comprises holding said pressurized
liquid in a pre-loaded, pressurized chamber.
12. The method of claim 9, wherein the step of moving said piston
under the force of said hydraulic pressure further comprises:
introducing a pneumatic pressure into a pneumatic to hydraulic
pressure converter, and
outputting said hydraulic pressure from said pressure
converter.
13. The method of claim 9, wherein the pressurized liquid is
dispensed onto a substrate having a relative speed of movement with
respect to said dispensing gun, and the method further
comprises:
sensing said relative speed of movement, and
controlling the force of said hydraulic pressure in proportion to
the sensed relative speed of movement.
14. A method of dispense-coating a surface of a substrate with
liquid from a valve mechanism of a dispensing gun operated by a
hydraulic actuator operatively coupled with a flow control device,
the method comprising:
discharging pressurized hydraulic fluid from said hydraulic
actuator to open said valve mechanism and thereby dispense said
liquid onto the substrate, and
adjusting the flow of said pressurized hydraulic fluid from said
hydraulic actuator to vary at least one of an opening extent, an
opening speed and a closing speed of said valve mechanism.
15. The method of claim 14 further comprising:
controlling the flow of said pressurized hydraulic fluid in
proportion to a relative speed of movement between said dispensing
gun and said substrate.
16. The method of claim 14 further comprising:
sensing said relative speed of movement, and
varying the flow of said pressurized hydraulic fluid in proportion
to the sensed relative speed.
Description
This application is being filed in accordance with 35 U.S.C. .sctn.
119 and claims the priority of Japanese Patent Application No.
10-016350 which is fully incorporated by reference herein.
1. Field of the Invention
The present invention pertains to a technique for using a
dispensing gun having a valve mechanism to dispense and coat a
liquid such as an adhesive, sealant, sealing agent, coating agent,
etc. onto the surface of a substrate material in a linear manner
from the nozzle of the aforesaid dispensing gun. Furthermore, the
liquids used in the present invention include those made liquid by
heating and melting, such as thermoplastic resins.
2. Background of the Invention
Dispense-coating is widely used at present in liquid crystal board
manufacturing processes and in electronic board manufacturing
processes, etc. A dispensing gun having a valve mechanism is moved
relative to a substrate material which is being coated and, while
this happens, a liquid such as an adhesive, sealant, sealing agent,
coating agent, etc. is dispensed from the nozzle of the aforesaid
dispensing gun and a line is drawn on the surface of the substrate
material.
A known example of a dispensing gun apparatus having a valve
mechanism and used in the aforesaid conventional liquid dispense
coating method is the dispenser for dispensing small amounts of
liquid disclosed in Examined Japanese Utility Model Application Hei
7-33907. This apparatus uses a solenoid actuator for the valve
mechanism's opening and closing action, and its details are
described in the aforesaid publication. This publication lacks an
explanation of the substrate material which is being coated and the
relationship between the substrate material and the dispenser, but
the apparatus is constituted so that the dispenser and substrate
material which is being coated can move relative to one another.
For example, it is constituted so that the dispenser moves relative
to the substrate material or so that the substrate material moves
relative to the dispenser by means of a robot device, etc., which
can move along the X axis and Y axis.
Another example is shown in FIG. 4, which shows an example which
uses a pneumatic actuator for the valve mechanism's opening and
closing action. That is, FIG. 4 shows the schematic of an apparatus
for dispense-coating liquid with an air-operated dispensing gun 51
supplied by a liquid supply apparatus 52. A solenoid operated valve
53 turns the air on and off for operating dispensing gun 51, and
solenoid operated valve 53 opens and closes according to a control
signal from control apparatus 54. An air supply source 55 is
connected to valve 53.
Dispensing gun 51 shown in FIG. 4 is constituted so that dispensing
gun 51 and substrate material 56, which is being coated, can move
relative to one another. Dispensing gun 51 moves relative to
substrate material 56 or substrate material 56 moves relative to
dispensing gun 51 using a robot apparatus, not shown, which can
move along the X axis and Y axis. In a liquid dispense-coating
apparatus constituted in this manner, when solenoid operated valve
53 receives a control signal from control apparatus 54 and opens,
operating air from air supply source 55 is supplied to actuator
part 51a of dispensing gun 51. When this happens, piston 57 is
pushed upward against the pressure of spring 58. Needle 59, which
constitutes the valve mechanism of gun 51, is directly linked to
piston 57, so it is pulled upward at the same time and the valve
mechanism opens.
Liquid supplied from liquid supply apparatus 52 is dispensed from
nozzle 60 when needle 59 opens. This liquid 61 is dispensed onto
substrate material 56, which is moving relative to dispensing gun
51. When coating ends, solenoid operated valve 53 is switched by
the control signal from control apparatus 54, and the air pressure
pushing piston 57 upward is released and becomes atmospheric
pressure. Thus, piston 57 is pushed downward by the force of spring
58, and needle 59 closes the valve mechanism and dispensing of
liquid stops.
FIG. 5 shows the liquid coating pattern and the opening and closing
action of the valve mechanism in a linear liquid coating pattern
using the dispenser for dispensing small amounts of liquid
disclosed in the aforesaid Examined Utility Model Application Hei
7-33907 and the dispensing gun shown in FIG. 4. That is, FIG. 5 is
a model drawing showing the relationship between valve mechanism
opening and closing action 62 and coating pattern 61. The X axis in
the drawing is time, so the lower line indicates the valve
mechanism's opening and closing action 62. Synchronized with this
and above it is liquid coating pattern 61. Of course, this drawing
is enlarged and exaggerated in a model fashion, so it is not
surprising that an actual liquid coating pattern 61 would have an
extremely narrow line width H of about 50 to 150 microns. As is
clear from FIG. 5, the valve mechanism is open from the start of
coating until the end of coating in a conventional coating method,
and the drawing shows that at coating end point A the coating
amount suddenly increases and the line width widens.
The liquid coating method described above has the following types
of problems. The first problem, as shown in FIG. 5, is that there
is a sudden increase in the coating amount at coating end point A.
This makes the line width of coating end point A three to five
times wider than the normal coating pattern line width H, and this
leads to a decrease in product quality. For example, when applying
an adhesive or spacer to glue liquid crystal glass, there is too
much adhesive only at the coating end point area, so the glass
substrate'scombined thickness is thick just at that area, or the
adhesive oozes out to the surrounding area, and quality decreases.
This is a case in which the relative motion speed of the dispensing
gun and substrate material is rigidly kept at a constant speed from
coating start until coating finish. The reason for this is that the
closing speed of the dispensing gun valve mechanism at the coating
end point is fast--from 500 to 1000 mm/sec--as the needle is
pressed down, so the needle acts like a piston pump and the liquid
in the nozzle part is pushed out in one stroke.
A second problem is that a bubble 63 often occurs near coating
start point B. This is readily apparent when coating with a
material which contains dissolved oxygen, such as a UV curing
resin, etc. The main cause is that, when coating starts, the needle
of the dispensing gun is pulled upward at high speed, as described
previously, so the liquid pressure of the coating solution at the
needle tip temporarily has negative pressure, and this results in
cavitation, and the dissolved oxygen forms tiny bubbles. These
bubbles accumulate and gradually become larger, and the bubbles
appear at the coating surface without being destroyed. Experience
shows that bubble 63 has a diameter of about 100 .mu.m.
Bubble 63 appears conspicuously near dispensing start point B, and
stops occurring as dispensing continues and becomes stable. If this
sort of phenomenon occurs during adhesive coating when gluing disks
in the DVD (digital video disk) manufacturing process, for example,
it causes crucial problems when writing data to a DVD or when
reading the data.
A third problem accompanies the trend to high-function robots,
etc., and is a problem which occurs in a coating operation while
the relative motion speed of dispensing gun 51 and substrate
material 56 is undergoing variable speed control. The width of the
coating line becomes narrow when the relative motion speed is fast,
and the width of the coating line becomes broad when the relative
motion speed is slow.
The inventor and others believed that the aforesaid first and
second problems--that is, the sudden increase in dispensing amount
at the coating end point and the formation of bubbles at the
coating start point--were caused by the suddenness of the speed of
the opening action and closing action of the valve mechanism (that
is, the needle of the gun), so they could be solved if the speed of
the opening action and closing action were slowed to some extent.
However, the result of experiments found that with solenoid
actuators and pneumatic actuators it was nearly impossible to
adjust the operating speed. That is, in the case of solenoid
actuators, even if the voltage or current values are varied, when
the excitation force exceeds a threshold value the actuator's iron
core operates in one stroke from start point to stop point. Also,
the air in pneumatic actuators is compressible, so even if the air
pressure is changed gradually, when the action start pressure is
exceeded it operates in one stroke from piston start point to stop
point. The third problem--variation in coating line width when
coating while relative motion speed undergoes variable
motion--could be solved by controlling the valve mechanism'sextent
of opening in proportion to the motion speed and variably
controlling the dispensing amount, but in solenoid actuators and
pneumatic actuators this sort of control--that is, causing tiny
actions--is impossible.
SUMMARY OF THE INVENTION
The present invention is one which takes into account the
aforementioned problems. In one aspect, the invention pertains to a
method for dispense-coating the surface of a substrate material
with liquid from a liquid dispense-coating apparatus constituted so
that a dispensing gun and a substrate material undergo relative
motion. One object is to provide a liquid coating technique which
prevents widening of the coating line width due to a sudden
increase in coating amount at the coating end point. Another object
is to prevent the formation of bubbles near the coating start
point. Yet another object is to make the coating line width
constant even when the relative motion speed of the dispensing gun
and substrate material undergoes variable speed control.
To achieve the various advantages of this invention, the opening
and closing action of a dispensing gun valve mechanism is performed
by a hydraulic actuator. A flow control device is provided in a
liquid pressure supply circuit including the hydraulic actuator,
and the liquid flow is controlled by regulating the flow control
device to thereby control the opening speed and/or closing speed of
the valve mechanism.
The present invention also contemplates a speed control apparatus
for a liquid dispensing gun valve mechanism wherein the speed
control apparatus includes a hydraulic actuator. Also in accordance
with the invention, a flow control device is provided in a liquid
pressure supply circuit including the hydraulic actuator, and the
liquid flow is controlled by regulating the flow control device to
thereby control the opening speed and/or closing speed of the valve
mechanism.
Additionally, the present invention contemplates a method for
dispense-coating the surface of a substrate material with liquid
from a valve mechanism operated by a control apparatus similar to
that described above, and further constituted so that the opening
and closing speed of the valve mechanism is controlled by
regulating the flow control device. The liquid supply amount of the
hydraulic actuator is controlled in proportion to a relative speed
of movement between the dispensing gun and the substrate material,
and further coats the substrate with liquid while regulating the
extent that the valve mechanism is open.
As mentioned above, the present invention generally relates to the
act of opening and closing a liquid dispensing valve mechanism with
a hydraulic actuator. Liquids are generally incompressible, so
their volume does not change even after the application of
pressure. Therefore, the speed of the hydraulic actuator is
proportional to the liquid supply speed to the hydraulic actuator.
The liquid flow can be controlled by providing a flow control
device in the liquid pressure supply circuit supplying the
hydraulic actuator and regulating the flow control device, and the
aforesaid dispensing gun valve mechanism opening and closing speed
can be controlled.
Before an actual coating operation takes place according to a
preferred embodiment of the invention, a number of tests are
carried out to match coating parameters such as the physical
properties of the coating liquid and to empirically determine the
valve mechanism opening speed at which bubbles do not form at the
coating start point and the valve mechanism closing speed at which
there is not a sudden increase in dispensing amount at the coating
end point. By adjusting and setting the aforesaid flow control
device to match this speed it is possible to prevent the formation
of bubbles at the coating start point and to prevent a sudden
increase in dispensing amount at the coating end point.
Furthermore, by using an incompressible liquid it is possible to
adjust the extent to which the valve mechanism opens. That is, the
amount of movement of the hydraulic actuator is proportional to the
volume of liquid supplied to the hydraulic actuator, so by
controlling the volume of liquid supplied to the hydraulic actuator
it is possible to adjust the extent to which the valve mechanism
opens. This makes it possible to freely regulate the amount of
liquid dispensed from the dispensing gun, and this is a major
benefit. That is, by regulating the extent of opening of the valve
mechanism in proportion to the relative motion speed of the
dispensing gun and substrate material it is possible to maintain a
constant coating line width even if the relative motion speed of
the dispensing gun and substrate material varies.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic, partially cross-sectioned view of a first
embodiment of the present invention.
FIG. 2 is a schematic, partially cross-sectioned view of a second
embodiment of the present invention.
FIG. 3 is a schematic, partially cross-sectioned view a third
embodiment of the present invention.
FIG. 4 is a schematic, partially cross-sectioned view of a
conventional liquid coating apparatus.
FIG. 5 illustrates the relationship between the valve mechanism
opening and closing timing and coating pattern in a conventional
coating method.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the first embodiment shown in FIG. 1, a cylinder unit 1a, which
constitutes a hydraulic actuator, is provided in a dispensing gun
1, and a piston 7 is housed inside cylinder unit 1a. A liquid
supply apparatus is connected to dispensing gun 1. A solenoid
operated valve 3 controls primary on/off air for opening and
closing dispensing gun 1. Solenoid operated valve 3 is opened and
closed by a control signal from control apparatus 4. An air supply
source 5 is connected to valve 3 for operating gun 1. A
pneumatic/hydraulic converter 13 converts air pressure into liquid
pressure. A flow control valve 14 is connected between converter 13
and gun 1 by a fluid line or circuit 12.
In the system shown in FIG. 1 dispensing gun 1 and substrate
material 6 move relative to one another. Dispensing gun 1 moves
relative to substrate material 6 or substrate material 6 moves
relative to dispensing gun 1 using a robot apparatus or the like
which can move along the X axis and Y axis. In a liquid
dispense-coating apparatus constituted in this manner, when a
control signal is received from control apparatus 4 and solenoid
operated valve 3 opens, operating air from air supply source 5 is
supplied to pneumatic/hydraulic converter 13, and energy is
converted from air pressure to liquid pressure. The converted
liquid pressure is supplied from pneumatic/hydraulic converter 13
to cylinder unit 1a, which constitutes the hydraulic actuator of
dispensing gun 1, via flow control valve 14 provided in hydraulic
supply circuit 12. When this happens, piston 7 is pushed upward
against the pressure of spring 8. Needle 9, which constitutes the
valve mechanism of dispensing gun 1, is directly linked to piston
7, so it is pulled upward at the same time and the valve mechanism
opens.
Liquid 11 supplied from liquid supply apparatus 2 is dispensed from
nozzle 10 when needle 9 opens, and the liquid is coated in a line
11 on the surface of substrate material 6, which moves relative to
dispensing gun 1. When coating ends, solenoid operated valve 3 is
switched by a control signal from control apparatus 4, and the air
pressure supplied to pneumatic/hydraulic converter 13 is released
and becomes atmospheric pressure. The liquid pressure pushing
piston 7 upward is also released and returns to pneumatic/hydraulic
converter 13 through flow control valve 14 provided in liquid
pressure supply circuit 12. Piston 7 is then pushed down by the
force of spring 8, and needle 9 closes to stop the dispensing of
liquid 11. Thus, the speed of the opening action and closing action
of needle 9 can be freely regulated by regulating flow control
valve 14.
Before an actual coating operation takes place, a number of tests
are carried out while regulating flow control valve 14 to match
coating parameters, such as the physical properties of the coating
liquid, and to determine the valve mechanism opening speed at which
bubbles do not form at the coating start point, and to determine
the valve mechanism closing speed at which there is not a sudden
increase in dispensing amount at the coating end point. By
adjusting and setting the flow control valve to a suitable speed it
is possible to prevent the formation of bubbles at the coating
start point and to prevent a sudden increase in dispensing amount
at the coating end point.
The second embodiment, shown in FIG. 2, applies to a type of
dispenser which is provided with a liquid already loaded into a
chamber called a syringe or cartridge. In the embodiment shown in
FIG. 2, a dispensing gun apparatus 20 and a substrate material 26
can move relative to one another. For example, the dispensing gun
apparatus 20 moves relative to substrate material 26 or substrate
material 26 moves relative to dispensing gun apparatus 20 by means
of a robot device, not shown, which can move along the X axis and Y
axis.
A solenoid operated valve 23 controls primary on/off air for
opening and closing the valve mechanism of dispensing gun apparatus
20. Solenoid operated valve 23 is opened and closed by a control
signal from a control apparatus 24. An air supply source 25 is
connected to valve 23. A pneumatic/hydraulic converter 33 converts
air pressure into liquid pressure, and provides pressurized liquid
to a flow control valve 34.
Cylinder unit 21a, which constitutes a hydraulic actuator, is
provided in a body 21 of dispensing gun apparatus 20, and a piston
27 is housed inside cylinder unit 21a. A chamber 35, generally
referred to as a syringe or cartridge, is preloaded with liquid 31.
Flange unit 35a is provided in the upper part of chamber 35; it is
partially cut out in the circumferential direction. Meanwhile,
catch unit 21b is provided in gun body 21 to correspond to flange
unit 35a of chamber 35 and part is cut out in the circumferential
direction. Chamber 35 is attached to gun body 21 by inserting
flange unit 35a into catch unit 21b and rotating it a specified
amount. A seal 36 made of an elastic body is provided as shown.
A screw unit 35b is provided in the tip of chamber 35, and a nozzle
30 is screwed onto screw unit 35b. The valve mechanism of gun 20 is
constituted by nozzle 30 and the tip of a needle 29 mounted on the
aforesaid piston 27. A spring 28 presses piston 27 downward.
In a liquid dispense-coating apparatus constituted in this manner,
when a control signal is received from control apparatus 24 and
solenoid operated valve 23 opens, operating air from air supply
source 25 is supplied to pneumatic/hydraulic converter 33, and
energy is converted from air pressure to liquid pressure. The
converted liquid pressure is supplied from pneumatic/hydraulic
converter 33 to cylinder unit 21a, which constitutes the hydraulic
actuator of dispensing gun apparatus 20, via flow control valve 34
provided in hydraulic supply circuit 32. When this happens, piston
27 is pushed upward against the pressure of spring 28. Needle 29,
which constitutes the valve mechanism of dispensing gun apparatus
20, is directly linked to piston 27, so it is pulled upward at the
same time and the valve mechanism opens. Then liquid 31, which was
previously loaded into chamber 35, is constantly pressurized by the
pressurized air from air supply source 25, so it is dispensed from
nozzle 30 by the valve mechanism opening action, and coated in a
line 31 on the surface of substrate material 26, which moves
relative to dispensing gun apparatus 20.
When coating ends, solenoid operated valve 23 is switched by a
control signal from control apparatus 24, and the air pressure
supplied to pneumatic/hydraulic converter 33 is released and
becomes atmospheric pressure. The liquid pressure pushing upwardly
on piston 27 is also released and returns to pneumatic/hydraulic
converter 33 through flow control valve 34 provided in liquid
pressure supply circuit 32. Piston 27 is pushed down by the force
of spring 28, and needle 29 closes the valve mechanism to stop the
dispensing of liquid 31. The speed of the opening action and
closing action can be freely regulated by regulating flow control
valve 34.
The third embodiment, shown in FIG. 3, is one which uses a liquid
pressure supply apparatus capable of variable volume control. That
is, instead of solenoid operated valve 23 and pneumatic/hydraulic
converter 33 in the second embodiment, the third embodiment
provides liquid pressure supply apparatus 47, which is capable of
variable volume control, and also provides speed detection
apparatus 48, which detects the relative motion speed of substrate
material 26 and dispensing gun apparatus 20. In other respects,
this embodiment is essentially the same as the second embodiment.
Therefore, constituent units which have the same function as in the
second embodiment are given the same reference numbers, and
detailed discussion thereof shall be omitted.
Liquid pressure supply apparatus 47 uses stepping motor 49, and
functions so that the liquid pressure supply amount can be variably
controlled in proportion to a pulse signal which is the control
signal from control apparatus 24. In a liquid dispense-coating
apparatus constituted in this manner, when a relative motion speed
signal between dispensing gun apparatus 20 and substrate material
26 detected by speed detection apparatus 48 is introduced to
control apparatus 24 as the input signal, it is incremented by an
addition function of control apparatus 24, and a pulse signal
proportional to speed is output to stepping motor 49, and stepping
motor 49 is controlled. By doing so, a liquid pressure volume
proportional to relative motion speed is supplied from liquid
pressure supply apparatus 47 to cylinder unit 21a via flow control
valve 34 provided in liquid pressure supply circuit 32. When this
happens, piston 27 is pushed upward against the pressure of spring
28 only by the supplied amount of liquid pressure volume.
Needle 29 is directly linked to piston 27 so it is pulled upward at
the same time only by the amount of liquid pressure, and the valve
mechanism also is opened only by the liquid pressure amount. Liquid
31, which was previously loaded into chamber 35, is then constantly
pressurized by the pressurized air from air supply source 25, so it
is dispensed from nozzle 30 by the valve mechanism opening action,
and coated in a line 31 on the surface of substrate material 26
which moves relative to dispensing gun apparatus 20.
When the pulse signal from control apparatus 24 diminishes in
proportion to relative speed, only the diminished amount of liquid
pressure in cylinder 21a returns to the liquid pressure supply
apparatus from cylinder unit 21a, and the extent to which the valve
mechanism opens is regulated. By doing so, the amount of liquid 31
dispensed also diminishes. That is, by regulating the extent to
which the valve mechanism opens in proportion to the relative
motion speed of the dispensing gun apparatus and substrate
material and by regulating the amount of liquid dispensed, it is
possible to maintain a constant coating line width even if the
relative motion speed of the dispensing gun apparatus and substrate
material changes.
Furthermore, in the third embodiment a relative motion speed signal
between dispensing gun apparatus 20 and substrate material 26
detected by speed detection apparatus 48 is introduced to control
apparatus 24 as the input signal, but instead of this it is
possible to introduce a relative motion signal from a robot device
(not shown in the drawing) which can move along the X axis and Y
axis, etc., as the input signal.
The embodiments described above are preferred embodiments, and a
person with skill in the relevant art could easily modify them to
other configurations without departing from the scope of the
present invention. The important thing in the embodiments is that a
hydraulic actuator is used to open and close the valve mechanism in
the dispensing gun or dispensing gun apparatus; otherwise, their
constitution can be freely modified. For example, they could be
easily combined with the constitution disclosed in the previously
discussed Examined Utility Model Application Hei 7-33907 or with
other known constitutions. Therefore the scope of the present
invention should be defined only by the claims.
* * * * *